If INDEED it is pus, then definitely pull the sensor and put in another one at least a few inches away from the infected site. clean it will with alcohol and add some antibiotic ointment...and WATCH carefully. If it turns red, mark the lines around the edges in pen, and if it spreads, contact your MD ASAP to be put on an antibiotic.

I have been on MM CGMS for over a year now, and have had no issues with pus near the sensor.

Keep an eye on it, keep it clean, and be liberal with the antibiotic ointment/cream (bacitracin, neosporin, triple antibiotic, etc)